Semiconductor wafer manufacturing technology utilizes very sophisticated wafer processing procedures and complicated manufacturing systems to produce semiconductor wafers. Each wafer goes through several process steps such as resist spinning, etching, dielectric layer depositions, metal depositions, and different encapsulation layer processes. These process steps are performed to define and etch pre-designed patterns onto the silicon wafers. The wafers are subjected to several high temperature processes, with temperatures ranging from 400.degree. C. to 1400.degree. C. It is during these multiple processing and deposition processes involving multiple layers of different types of metals and dielectric that a great deal of stress is built up in the layers on the wafer. The stress is generated due to differences in coefficients of expansion of the individual layers that are in direct contact with each other.
The ever-increasing demand for reduced product sizes and miniaturization of computers has forced semiconductor manufacturers to shrink all the parts that go into electronic products. Common examples of reduced-size products are laptop computers, notebook computers, mobile telephones, etc. In order to manufacture these products, manufacturers have to make smaller displays and keyboards, and to produce thinner PC Boards. Manufacturers must also reduce the thickness of assembled IC packages so as to satisfy the miniaturization parameters.
In order to meet the challenges of Thin Small Outline Packages (TSOP), semiconductor manufacturers have been forced to reduce the thickness of silicon wafers before sawing and dicing operations. Historically, these wafers were shipped overseas to assembly houses or locally to subcontractors for sawing and assembly operations. The wafer thickness ranged from 30 mils for 200-mm diameter wafers to 22 mils for 100-mm diameter wafers. These thickness ranges allowed manufacturers to ship wafers in plastic containers, commonly referred to as "jelly jars". The most commonly used containers were round with a lid which could be screwed onto the top. Wafers were placed in these jars with foam cushions on the bottom and on top. The wafers were separated and protected by sheets of thin cleanroom paper, or TYVEK (a product manufactured by DuPont Company).
Most manufacturers find it very difficult to package wafers in the plastic jars. Placing wafers in these plastic containers has always been a manual operation, which is very time consuming and labor intensive. In addition, when the subcontractors received wafers packed in the plastic containers, the subcontractors would have to remove the top lid and flip over the jar to remove the silicon wafers. This method was very cumbersome, and subjected the wafers to an unacceptably high risk of damage.
The packaging and shipping of wafers for further processing becomes even more critical when wafers are shipped after processes which reduce the overall thickness of the wafer, such as a Wafer Grinding Operation. Ground wafers, whose thicknesses range from about 10 mils for 200 mm wafers to about 4 mils for 100 mm, are very thin and fragile, and can easily be broken during packaging, shipping, or unpacking.
Accordingly, it is an object of the present invention to provide a shipping container that is suited to shipping wafers that have been ground to a very small thickness.
It is a further object of the present invention to provide a wafer shipping container that can be loaded and unloaded with vacuum wands or tweezers without breaking wafers.
It is a still further object of the present invention to provide a wafer shipping container that can be used in automated wafer transferring systems.
It is still another object of the invention to provide wafer shipping containers that can be stacked on top of each other so as to reduce shipping costs.